1. Field of the Invention
The present invention relates to a method and an apparatus for carrying out image processing for changing density and tone of digital color image data obtained by a digital camera or a scanner. The present invention also relates to a computer-readable recording medium storing a program to cause a computer to execute the image processing method.
2. Description of the Related Art
Image processing systems for reproducing digital image data obtained by digital still cameras (hereinafter called digital camera) and digital image data obtained by reading images recorded on films as hard copies such as prints or as soft copies on display screens have been proposed. In such an image processing system, digital image data are also provided by being recorded in a recording medium such as a CD-R. In the case where such an image obtained by a digital camera or a scanner is printed, the image is expected to have as high a quality as a photograph printed from a negative film.
For this reason, printing is carried out after image processing for correcting a density and a tone of digital image data has been carried out. Especially, in the case where an image includes a person, image processing is carried out on image data so as to change a skin color to have an adequate density or tone, since the skin color is a substantially important color. For example, in an image photographed by using flash, a skin color looks too light in some cases, and the skin color can be darkened by increasing the density of the image. Furthermore, in the case of a dark skin color caused by backlight, the skin color can be lightened by decreasing the density.
However, although the skin color can be darkened by increasing the density, saturation also decreases and the skin color does not give a favorable impression. Furthermore, if the density is decreased in such a manner that a tone curve for changing the tone is downwardly convex, the skin color looks bluish, also giving an impression of being unhealthy. As has been described above, changing the density and the tone of an image leads to reproduction of a dull color in the image.